It is thought that neutrophilic leukocytes show a germicidal activity to foreign invaders in living bodies by a wondering reaction, a phagocytic activity, generation of superoxide radical (O.sub.2.sup.-) and release of lysosomal enzyme and play an important role in protection of living body. While neutrophilic leukocytes have the above reaction for living body protection, it has been made clear that the superoxide radical released by tissues or neutrophilic leukocytes during ischemia of tissues and subsequent blood reperfusion or during acute inflammation at early stage destroys cells, causing functional disturbances of tissues [B. R. Lucchesi: Annual Review of Pharmacology and Toxicology, Vol. 26, p. 201 (1986); B. A. Freeman et al.: Laboratory Investigation, Vol. 47, p. 412 (1982); E. Braunwald, R. A. Kloner: Journal of Clinical Investigation, Vol. 76, p. 1713 (1985); J. L. Romson et al.: Circulation, Vol. 67, p. 1016 (1983)].
It is described in Japanese Patent Publication No. 15935/1971 that compounds represented by the following general formula: ##STR2## (wherein, R.sup.1 is a group selected from the group consisting of a hydrogen atom and a straight-chain or branched-chain lower alkyl group of 1-5 carbon atoms; R.sup.2 is a group selected from the group consisting of a lower alkyl group of 1-5 carbon atoms, a phenylalkyl group which may be substituted with a lower alkyl or lower alkoxy group of 1-5 carbon atoms or with one or more halogen atoms, and a phenyl group; A is a group selected from the group consisting of a hydrogen atom, a halogen atom, a hydroxyl group and a lower alkyl or lower alkoxy group of 1-5 carbon atoms), which have similar chemical structures to those of the thiazole derivatives of the present invention, have properties which are advantageous for fibrinolysis, platelet stickiness, ulcers and immunological treatments and can be used for prevention and treatment of thrombosis, arteriosclerosis, gastric ulcer and hypersecretion.